The vibration and noise which occur in our living environment have been pointed out as one of the causes of public nuisance. An increase in the accuracy required of a precision machine has given rise to the necessity for providing means for preventing the vibration of the machine itself. One of the approaches which have hitherto been made to cope with those problems and requirements is to use a material having an outstandingly high power of damping vibration (a vibration-damping material) for making any component that is a source of vibration.
There have been developed a number of alloys which are macroscopically uniform and have a high power of damping vibration. The main examples thereof are flake graphite cast iron, some iron-based alloys, a Mg-Ni alloy, Cu-Mn alloys and a Ni-Ti alloy. The iron-based alloy can be said from the standpoints of strength and cost to be practically the best material for any parts that are used in a large quantity.
The known iron-based alloys include an Fe-Al alloy as proposed in Japanese Patent Publication No. 803/1977. This alloy is claimed to have a high power of damping vibration if it contains 2 to 8% Al. Japanese Patent Publication No. 28982/1981 proposes an iron-based alloy containing 0.4 to 4% Si and 0.1 to 1.5% Mn, and having a ferrite grain size number of 5 or below, and states that the Si and Mn which it contains fix N to eliminate any hindrance to the motion of dislocations which absorb vibration energy.
The vibration-damping properties of the known alloys as hereinabove described are, however, not necessarily satisfactory for the recent requirements which call for a very high level of vibration damping.
Under these circumstances, I, the inventor of this invention, have found that an alloy made by adding a specific proportion of Al or Si, or particularly both, to Fe exhibits an outstandingly high power of damping vibration which has hitherto not been possible.